Norbornane is a cyclic compound found in or derivable from the residual heavy hydrocarbons in the bottoms of distillation towers in light hydrocarbon production facilities. Various derivatives of norbornane have been made, among them the bis(methylamine). It is this compound which has been phosphonomethylated which is the subject of the present invention.
It is well known that amines such as ethylenediamine and diethylenetriamine can be reacted with formaldehyde and phosphorus acid to obtain methylene phosphonate derivatives of the amine in which the methylene phosphonate group ##STR1## substitutes for the amine hydrogens (U.S. Pat. No. 3,288,846).
The use of methylenephosphonic acid substituted alkylene polyamines for metal ion control at less than stoichiometric amounts was suggested in a patent (U.S. Pat. No. 2,609,390) issued in 1952. Later a water dispersible polymeric amine chelating agent which included alkylene phosphonate derivatives was indicated as having "threshold" effects in scale inhibition applications (see U.S. Pat. No. 3,331,773), this term being used to describe the use of the agent in less than stoichiometric amounts. The diamine and polyamine methylenephosphonate derivatives are taught and claimed in U.S. Pat. Nos. 3,336,221 and 3,434,969, respectively. Some of the products disclosed in these two patents are available commercially and are recommended as scale inhibitors when applied in threshold amounts.
Other patents which disclose heterocyclic nitrogen containing compounds which are useful as chelating agents and may be employed in threshold amounts are U.S. Pat. Nos. 3,674,804; 3,720,498; 3,743,603; 3,859,211; and 3,954,761. Some of the compounds included therein are heterocyclic compounds having the formulas: ##STR2## wherein R is hydrogen or alkyl and M is hydrogen, alkali metal, ammonium or a di- or triethanolamine radical; ##STR3##
Certain phosphonic acid derivatives of the aliphatic acids can be prepared by reacting phosphorous acid with acid anhydrides or acid chlorides, e.g. the anhydrides or chlorides of acetic, propionic and valeric acids. The compounds prepared have the formula ##STR4## wherein R is a lower alkyl radical having 1 to 5 carbon atoms. The method of making and use of these products is described in U.S. Pat. No. 3,214,454. The use of threshold amounts to prevent calcium precipitation is disclosed and claimed therein.
It has now been discovered that new chelating and threshold agents for inhibiting precipitation of metal ions can be made from the bis(methylamine) derivatives of norbornane. This compound has the structure ##STR5##
This compound is also known by the more formal name of 2(3), 5(6)-bis[aminomethyl]bicyclo(2,2,1)heptane. Its derivatives are those with various substituents replacing the primary amine hydrogens.